Brain Scans

Question 1

What is Post- mortem?

Answer 1

The examination of the brain after a person has died.

Question 2

What are examples of Post- mortem?

Answer 2

• Brocca (1861)
• Charles Whitman (1966)
• Phineas Gage (1860)

Question 3

What’s an EEG’s [Electroencephalogram]?

Answer 3

• Small sensors/ electrodes are attached to the scalp. They pick up electrical signals produced when brain cells send messages to each other.
• The machine is only recording the activity of your brain. It does not stimulate it.
  A neurologist will monitor for any unusual readings in your brain wave patterns.

Question 4

Dement and Kleitman (1957)?

Answer 4

• Used EEG’s to explore different stages of sleep.
• As people sleep their brain waves slow down.
• During Rapid Eye movement [REM] sleep brain waves increase.
• Found that REM sleep correlated with dream recall compared to other stages of sleep.

Question 5

What is a CAT Scans [Computed axial tomography]?

Answer 5

• Rotating x- ray machine to create 3D images.
• Lasts 10-20 minutes.
• Non invasive but does use targeted radiation
• Can diagnose Cancer, tumour and structural damage as can detect normal and abnormal organs.
• Shoots narrow beams of X-rays through the body.
• The computer generates a 3D image from several 2D images of a slice of body. Typically 1 to 10mm thick.

Question 6

Johnstone et al (1979)?

Answer 6

Used CAT Scans to compare the brains of those with schizophrenia and people without schizophrenia.
Results:
Schizophrenia brains were different to normal brains as the ventricles [fluid filled spaces] were much larger.

Question 7

What is an MRI scans [Magnetic resonance imaging]?

Answer 7

• This type of scan uses strong magnetic fields and radio waves to produce detailed images of the inside of the body.
• Lasts longest amount 15- 90 minutes
• Non Invasive and no potential risks such as radiation

Question 8

How do MRI scans work?

Answer 8

• The human body is made up of water molecules. [Hydrogen and oxygen atoms]
• The atoms act like tiny magnets and sensitive to the magnetic field produced by the MRI scan.
• Short bursts of radio waves are sent to certain areas of the body knocking the atoms out of alignment.
• When the radio is turned off the protons realign and produce an electromagnetic signal that is translated by the computer into pictures.

Question 9

What is a PET Scans [Positron emission tomography]?

Answer 9

• Radioactive glucose (FDG) is injected into the patient.
• The brain uses glucose for energy, the more active parts using more glucose.
• This will leave a faint radioactive trace in the parts of the brain that have been most active.
• This can then be detected by a PET scan
• Duration 30 minutes
• Non-invasive treatment however patient is injected with a small amount of radioactive substance so can only be used a few times.

Question 10

Example of PET scans?

Answer 10

Rainer et al (1997):

• Used PET scans to compare brain activity in murderers and normal individuals.
• They found differences in areas of the brain such as the prefrontal cortex and the amygdala.
• Regions previously associated with aggressive behaviour.

Question 11

Strengths of EEG’s?

Answer 11

• Non invasive and readily available
• Low cost and low risk
• Good for monitoring epilepsy and identifying type of seizure.
• Can record brain activity immediately.
• Can have family members in the room with you

Question 12

Weaknesses of EEG’s?

Answer 12

• Can’t locate damaged area of the brain as electrical activity can be detected in several areas.
• Can’t discriminate between different brain areas.
• Is uncomfortable as electrodes are glued to the scalp

Question 13

Strengths of CAT scans?

Answer 13

• Most detailed in producing high quality images. [Images in 3D]
• Shows a range of different tissue types so can diagnose cancer and tumours for example.
• Faster and less sensitive so good choice for a trauma

Question 14

Weaknesses of CAT scans?

Answer 14

• Uses ionising radiation so limit to number of scans you can use.
• CAT scans can only provide structural information.
• Fewer CAT scans available then other hospital equipment such as X-rays
• Not as detailed as MRI scans

Question 15

Strengths of MRI scans?

Answer 15

• Safer than other types of scans as uses a magnetic field through the patient.
• Patients can use the machine repeatedly.
• MRI scans give more detailed images of soft tissue in the brain.
• Better for showing changes in the brain over time such as dementia.

Question 16

Weaknesses of MRI scans?

Answer 16

• Can take a long time, feel uncomfortable and some patients may feel highly claustrophobic.
• Use extremely loud noises because of the magnetic field.
• More expensive

Question 17

Strengths of PET scans?

Answer 17

• PET scans can reveal chemical information so therefore can distinguish between benign and malignant tumours.
• Can show the brain in action which is useful for psychological research.

Question 18

Weaknesses of PET scans?

Answer 18

• Extremely costly technique and not readily available.
• Radioactive substance used so can only be used a few times.
• PET scans are less precise the MRI scans